Suddenly no sound & no picture overnight: is my TV dead?
If you have static siugnal, sure TV is not dead.
Check the aerial cable, ensure it is well plugged in and getting signal.
If you are using a receiver box, check cables to TV and receiver (freeview, sat, cable etc.), try setting channels on receiver again, if it does not work but you get static, then either the cables or receiver are defective.
Test the TV on standalone , connecting it to an external antenna.
Tune again the channels, and save the preset.
If still no signal then the antenna socket on the TV may be defective.
Try using the TV with a DVD.
If you can watch DVDs, and TV is not keeping channels preset, and you tried all the above, at this point htere may be a fault in the tuner card inside tv.
Call the phone number listed on tv user manual to get support, and eventually repair it.